DNA damage and repair are thought to play roles in such diverse processes as carcinogenesis and aging. Radiation sensitivity and DNA repair will be studied in the small, free-living nematode Caenorhabditis elegans. As a post-doctoral fellow, I have isolated and mapped nine rad (for abnormal radiation sensitivity) mutants. This proposal specifically seeks to determine: (1) wild-type and mutant responses to individual and various combinations of DNA damaging agents; (2) wild-type and mutant radiation sensitivities as a function of life cycle; (3) epistatic interactions between the rad mutants; (4) whether the parental genotype can affect radiation sensitivity of the rad mutants; and (5) if photoreactivation and liquid holding recovery can be demonstrated, and if so, what effect(s) they have on aging. In addition, induction and repair of specific DNA damages will be assayed using alkaline gel electrophoresis and high pressure liquid chromatography.